By Valerie Volcovici

WASHINGTON, (Reuters) – Half of methane emitted by all U.S. well sites is due to low-producing wells. They account for only 6% of U.S. total production. A new report was released Wednesday.

Nature Communications published the study. It is the first time that a detailed look has been taken at over 560,000 “marginal oil and gas wells” in the United States. These wells account for more than 80% of all US well sites. The Environmental Protection Agency is about to announce new methane regulations for the oil-and gas sector.

After carbon dioxide, methane is second in climate change.

Environmental groups were critical of the proposed rule because it required only large well sites that emit more than three tonnes of methane annually to be monitored by the agency. This was a source of 86% of all leaks.

The report states that marginal wells emit less than 15 barrels per day of equivalent oil and produce methane at rates 6-12 times faster than the national average. This is equivalent to 10% of the gas they release into the atmosphere.

The EPA will overlook a vast source of methane if it doesn’t regulate those wells.

Mark Omara, an Environmental Defense Fund scientist and author of the study said that small-sized wells have a large methane footprint and should not be overlooked.

Nick Conger, spokesperson for the EPA, stated that the agency was informed of the contents by the report in its public comments period regarding the November proposal.

He stated in an email statement that “we are considering this, together with all the other comments we received,” and added, “The Agency expects to release a supplemental proposal later this year.”

Oil and gas industry organizations had asked the EPA for exclusion of smaller wells. This was based on the number of these wells as the cost of monitoring and repairs.

The report stated that field observations revealed that the main driver of methane emissions at low production sites was equipment “negligence” and “disrepair”. This can be avoided by frequent inspections and monitoring.

The proposed EPA Methane Rule would regulate methane emissions from current oil and gas operations. Oil and gas companies must routinely monitor 300,000.000 wells, and any infrastructure that might be affected for leaks. They are required to quickly repair methane-related problems.